新型结构转换体系力学性能研究

某高层住宅楼所设置的转换层,经比较分析,采用桁架体系。基于该种转换方式杆件实际受力和理论分析差距较大,在进行了充分计算之后,采取了几种构造保证措施,并对实体结构转换部位作了全方位监测,监测结果表明,该工程设计是成功的。为今后相似工程设计提供了借鉴。     

面向退役机电产品全生命周期的知识图谱统一建模方法研究

针对退役机电产品逆向物流信息追溯过程中时空分散度高、质量不确定性强、跨组织信息关联度弱等问题,基于知识图谱技术构建了退役机电产品全生命周期统一数据模型。首先提出了从跨组织多源数据到知识图谱构建和应用的全生命周期统一数据建模方法,然后提出了知识图谱构建关键技术,针对知识图谱构建过程中的实体关系联合抽取问题,建立了基于分段注意力融合机制的实体关系联合抽取模型,解决了实体关系重叠问题,并在标准数据集和退役机电产品领域数据集上进行测试,取得了很好的效果,最后建立了退役机电产品全生命周期信息追溯系统。知识图谱的构建实现了退役机电产品生命周期中跨组织信息的统一数据结构,为退役机电产品逆向物流信息追溯提供了强有力的支撑。     

Inhibitory effects of flavonoid glycosides isolated from the peel of Japanese persimmon (Diospyros kaki Fuyu) on antigen-stimulated degranulation in rat basophilic leukaemia RBL-2H3 cells

We found that two distinct flavonoid glycosides isolated from the peel of Japanese persimmon (Diospyros kaki Fuyu), isoquercitrin (Isq) and hyperin (Hyp), are capable of inhibiting antigen-stimulated degranulation in rat basophilic leukaemia RBL-2H3 cells. In order to elucidate the underlying mechanisms, we examined effects of Isq and Hyp on cellular responses induced by antigen stimulation. Treatment with both Isq and Hyp markedly inhibited antigen-stimulated elevation of intracellular free Ca²⁺ concentration and reactive oxygen species (ROS). Isq and Hyp did not affect NADPH oxidase (NOX) activity, but they possessed DPPH radical-scavenging activity similar to that of epigallocatechin gallate, a potent anti-oxidant, Finally, Isq and Hyp showed little or no effects on Ag-stimulated Syk activation or phosphorylation of signalling molecules. These results indicate that inhibition of antigen-stimulated degranulation by Isq and Hyp is mainly due to suppression of intracellular Ca²⁺ elevation, which is caused by direct scavenging of ROS that are generated by NOX. Our findings suggest that Isq and Hyp, isolated from the peel of persimmon, would be beneficial for alleviating symptoms of type I allergy.     

开发在Autocad环境下检测及修改声学仿真模型的命令

介绍了Autolisp语言的基本语法和Autocad图形中3DFACE实体数据表内容，阐明了几个在Autocad环境下检测及修改计算机声学仿真模型的命令的编写原理和方法，并用一个具体实例验证了这些命令。     

Electrochemically reduced titanocene dichloride as a catalyst of reductive dehalogenation of organic halides

We have studied a reaction between the reduced form of titanocene dichloride (Cp₂TiCl₂) and a group of organic halides: benzyl derivatives (4-Xentities/sbnd" class="glyphImg">C₆H₄CH₂Cl, X = H, NO₂, CH₃; 4-Xentities/sbnd" class="glyphImg">C₆H₄CH₂Br, X = H, NO₂, PhC(O); 4-Xentities/sbnd" class="glyphImg">C₆H₄CH₂SCN, X = H, NO₂) as well as three aryl halides (4-NO₂C₆H₄Hal, Hal = Cl, Br; 4-CH₃O-C₆H₄Cl). It has been shown that the electrochemical reduction of Cp₂TiCl₂ in the presence of these benzyl halides leads to a catalytic cycle resulting in the reductive dehalogenation of these organic substrates to yield mostly corresponding toluene derivatives as the main product. No dehalogenation has been observed for aryl derivatives. Based on electrochemical data and digital simulation, possible schemes of the catalytic process have been outlined. For non-substituted benzyl halides halogen atom abstraction is a key step. For the reaction of nitrobenzyl halides the complexation of Ti(III) species with the nitro group takes place, with the electron transfer from Ti(III) to this group (owing to its highest coefficient in LUMO of the nitro benzyl halide) followed by an intramolecular dissociative electron redistribution in the course of the heterolytic Centities/sbnd" class="glyphImg">Hal bond cleavage.The results for reduced titanocene dichloride centers immobilized inside a polymer film showed that the catalytic reductive dehalogenation of the p-nitrobenzyl chloride does occur but with a low efficiency because of the partial deactivation of the film due to the blocking of the electron charge transport between the electrode and catalytic centers.     

A novel route to α,ω-telechelic poly(-caprolactone) diols, precursors of biodegradable polyurethanes, using catalysis by decamolybdate anion

A new convenient route for the synthesis of poly(entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">-caprolactone) (PCL) with α,ω-telechelic diols' end-groups is presented. Synthesis of α,ω-telechelic PCL diols (HOPCLOH) was achieved by ring-opening polymerization (ROP) of entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">-caprolactone (CL) catalyzed with ammonium decamolybdate (NH₄)₈[Mo₁₀O₃₄] and using diethylene glycol (DEG) as initiator. Obtained HOPCLOH was characterized by ¹H and ¹³C NMR, FT-IR, GPC and MALDI-TOF. Comparative studies demonstrate that ammonium decamolybdate (NH₄)₈[Mo₁₀O₃₄] is better catalyst than Sn-octanoate (SnOct₂) toward CL polymerization in presence of DEG, under the conditions tested. A biodegradable poly(ester-urethane-urea) derivative was efficiently prepared from synthesized HOPCLOH. Obtained polymer shows minor differences with respect to the properties recorded for a poly(ester-urethane-urea) obtained from commercial HOPCLOH.     

Acid- and base-catalyzed hydrolyses of aliphatic polycarbonates and polyesters

Poly(propylene carbonate) (PPC) was synthesized by the zinc glutarate catalyzed copolymerization of carbon dioxide and propylene oxide (PO). Hydrolytic degradability of the PPC polymer was examined in tetrahydrofuran solutions containing 10 wt.% acidic or basic aqueous solutions of varying pH using viscometry and GPC analysis. Further, the hydrolysis behaviors of all PPC solutions were compared with those of poly(entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">-caprolactone) (PCL) and poly(d,l-lactic acid) (PLA). All polymers studied show higher degradability in strong basic conditions than in strong acidic conditions, but very low degradability in moderate acidic, basic and neutral conditions. Moreover, PPC is degraded less in strong acidic conditions than the polyesters, while in strong basic conditions, the polycarbonate is more easily degraded. The difference in degradabilities of these polymers in acidic conditions is associated with the different nucleophilicities of their carbonyl oxygen atoms, while in basic conditions the differences are associated with the different electrophilicities of the corresponding carbonyl carbon atoms. With regard to the hydrolysis results and the structural and chemical nature of the polymer backbones, degradation mechanisms are proposed for the acid- and base-catalyzed hydrolyses of PPC, PCL and PLA.     

Self-assembly through hydrogen-bonding and C–Hπ interactions in metal complexes of N-functionalised glycine

The complex [Ni(L1)₂(py)₂]. toluene (L1 is N-phthaloylglycinato and py is pyridine) was prepared from solid state reaction whereas co-crystals having composition 2[Ni(L1)₂(py)₃(H₂O)] · [Ni(L1)₂(py)₂(H₂O)₂] · 2py · 2H₂O was obtained from solution state reaction.     

Novel synthetic strategy toward shape memory polyurethanes with a well-defined switching temperature

Shape memory polyurethanes (SMPUs) have been synthesised via a novel synthetic methodology, resulting in an improvement of the phase separation in the multi-block structure of the polyurethane and in its shape memory properties. ABA block copolymers based on semi-crystalline poly(entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">-caprolactone) and amorphous poly(propylene oxide) (PPO) were used as precursor for the SMPUs. For their synthesis, poly(entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">-caprolactone) diols have been converted into isocyanate end-capped prepolymers by using a mixture of 3(4) isocyanato-1-methyl-cyclohexylisocyanate isomers, after which a coupling with low-T_g poly(propylene oxide) oligomers is done. The shape memory polymers are obtained by reaction of the ABA block copolymers with hexamethylenediisocyanate and 1,4-butanediol as chain extender. Using this new strategy, a flexible segment (PPO) was introduced between the hard and the switching segments of the SMPU. For comparison, SMPUs without flexible segment have also been prepared with the conventional synthetic route. DSC, isostrain experiments and cyclic shape memory tests revealed narrower switching temperatures for the SMPUs including a flexible segment.